Studies on genetic uniformity of Chowghat Green Dwarf and Malayan Green Dwarf varieties of coconut using molecular and morphometric methods
Two coconut varieties viz., Chowghat Green Dwarf (CGD) and Malayan Green Dwarf (MGD) were subjected to morphometric and molecular studies to assess their genetic uniformity. Since both these varieties possess traits for high yield and resistance to root (wilt) disease, they have already been released for cultivation in the root (wilt) disease prevalent tracts. Forty two CGD palms from ‘disease hotspots’ were analyzed using 43 simple sequence repeat (SSR) primers. Monomorphic bands were detected in all the CGD samples with 41 primers, which is an indication of its genetic uniformity. A single CGD palm showed polymorphism with two SSR primers. Forty eight MGD palms were analyzed using 24 SSR primers. The MGD palms clustered at 62 per cent similarity. Analysis of morphological and fruit component characters of CGD and MGD population revealed that both the populations were phenotypically uniform. Breeding behaviour studies revealed that both CGD and MGD were predominantly self pollinated, like other dwarf varieties of coconut. There was complete overlapping of male and female phases in almost 96 per cent of CGD palms. Almost 100 per cent self-pollination was ensured in these palms as male phase prolonged even after completion of female phase. However, only 60 per cent of the MGD palms showed complete overlapping and in the remaining 40 per cent palms, there was only partial overlapping of male and female phases. From the present study, it is inferred that breeding behavior and genetic uniformity could be highly correlated in coconut. Collection of seed nuts preferably from mother palms with overlapping of male and female phases could possibly ensure production of true to type progenies in dwarf varieties of coconut. Present study also indicated that molecular markers like SSRs may be used to identify genetically pure mother palms for varietal improvement programmes in coconut.